package demo;

import java.util.Stack;

public class MyQueue {
    //定义两个栈
    private Stack<Integer> s1;
    private Stack<Integer> s2;

    public MyQueue() {
        s1 = new Stack<>();
        s2 = new Stack<>();

    }
    //入到s1
    public void push(int x) {
            s1.push(x);
    }
    //出到s2
    public int pop() {
        if(empty()){
            return -1;
        }
        if(s2.empty()){
            while( !s1.empty()){
                s2.push(s1.pop());
            }
        }
            return s2.pop();
    }

    public int peek() {
        if(empty()){
            return -1;
        }
        if(s2.empty()){
            while( !s1.empty()){
                s2.push(s1.pop());
            }
        }
        return s2.peek();

    }

    public boolean empty() {
        return s1.empty() && s2.empty();
    }
}
